Light fixture with drop hinged diffuser



y 11, 1967 v. s. WINCE ETAL LIGHT FIXTURE WITH DROP HINGED DIFFUSER 2 Sheets-Sheet 1 Filed May 25, 1964 INVENTORS $4742 63 Mmce #420481 022541 ATTORNE ys July 11, 1967 v. s. WiNCE ETAL LIGHT FIXTURE WITH DROP HINGED DIFFUSER Filed May 25, 1964 2 Sheets-Sheet 2 I NV ENTORS ORNE Y5 United States Patent 3,330,952 LIGHT FIXTURE WITH DROP HINGED DIFFUSER Vearl S. Wince, Newark, Ohio, and Harry R. Lobdell, S okane, Wash, assignors of one-half to Holophane Company, Inc., New York, N.Y., a corporation of Delaware, and one-half to Columbia Electric and Manufacturing Co., Spokane, Wasin, a corporation of Washin on gt Filed May 25, 1964, Ser. No. 369,673

12 Claims. (Cl. 240147) The present invention relates to lighting fixtures.

In particular, the present invention relates to that type of lighting fixture where lamps, such as fluorescent lamps, are located in a lamp housing which has an open bottom in which a diffuser plate is accommodated so that when the lamps are illuminated the light therefrom will pass through the diffuser plate.

As is well known, it is necessary from time to time to change the fluorescent lamps. This requirement makes it essential that the diffuser plate of such a lighting fixture be capable of being displaced from its position located in and substantially filling the open bottom of the lamp housing to a position which will give free access to the interior of the housing so that a lamp can be changed, and then of course it is necessary to return the diffuser plate to its position located in the open bottom of the housing. These diffuser plates are generally made of a transparent plastic, and when it is necessary to change a lamp the individual who proceeds to move the diffuser plate very often encounters considerable difficulty because such plates are usually mounted in such a Way that they must be moved in a very precise manner in order to avoid breakage. Unless one knows just how the plate is to be moved it will become damaged, and even when one does know how to manipulate the plate so as to give access to the interior of the lamp housing, rather complex manipulations are involved.

Moreover, in order to enable the diffuser plates of fixtures of the above type to be mounted in the housing in one of at least a pair of interchangeable positions, there is a costly duplication of rather complex structure with conventional lighting fixtures,

It is accordingly an object of the present invention to provide a lighting fixture which will avoid the above drawbacks.

Thus, one of the objects of the present invention is to provide for a lighting fixture of the above type a diffuser plate and mounting therefor which will make it very easy for an individual to move the difiuser plate to a position giving free access to the interior of the housing without any possibility of damaging the diffuser plate.

A further object of the present invention is to provide a lighting fixture of the above type which does not require any duplication of structures to enable the plate to be mounted in either one of a pair of positions so that in this way the cost of the structure is reduced as compared to conventional structures.

Another object of the present invention is to provide for a fixture of the above type a lamp housing which is of an exceedingly simple construction having no complicated elements which are required to support the diffuser plate either in its closed or in its open position.

Still another object of the present invention is to provide a fixture of the above type with a construction which will compel the operator to perform the proper manipulations for giving access to the interior of the housing so that it is not necessary for the operator to remember precisely how the diffuser plate should be moved relative to the housing so as to give access to the interior thereof.

Also, it is among the objects of the present invention to provide a diffuser plate which even though it carries a structure in excess of that carried by conventional diffuser plates, to participate in the support of the plate in an open position giving access to the interior of the housing, nevertheless will not have any areas which undesirably block the passage of light through the diffuser plate.

The lighting fixture includes a lamp housing which has two pairs of opposed side walls terminating in a peripheral bottom portion which defines an open bottom of the housing, and one of these pairs of opposed side walls have at their bottom edges inwardly directed flanges which extend toward each other. The diffuser plate is located in and substantially fills the open bottom of the housing and has two pairs of opposed side edges the side edges of one pair of which respectively rests on these flanges. A structure of this latter type is fairly conventional.

In accordance with the invention, the other of the pairs of opposed side walls of the housing carry above the bottom edges thereof at least one pair of coaxial pins located adjacent and extending parallel to one of the flanges of the housing, and the diffuser plate itself carries at the other of its pair of opposed side edges a pair of book means which cooperate with the pair of coaxial pins to support the diffuser plate in a position hanging downwardly from these pins to give access to the interior of the housing.

The invention is illustrated by way of example in the accompanying drawings which form part of this application and in which:

FIG. 1 fragmentarily illustrates a fixture according to the present invention, the housing and the diffuser plate' being shown in FIG. 1 in a transverse sectional elevation with the section of FIG. 1 extending across the longer sides of the housing;

FIG. 2 is a fragmentary sectional elevation of the structure shown in FIG. 1, taken along the line 22 of FIG. 1 in the direction of the arrows;

FIG. 3 is a fragmentary perspective illustration of the diffuser plate as viewed from above and as seen at oneof its narrow side edges;

FIG. 4 shows how the diffuser plate of FIG. 1 is shifted preparatory to being swung to its open position;

FIG. 5 fragmentarily illustrates the difiuser plate during its movement to its open position; and

FIG. 6 shows the difiuser plate, fragmentarily, hanging in its open position giving access to the interior of the lamp housing.

Referring now to the drawings, it will be seen that the lighting fixture illustrated therein includes a lamp housing 10 made of any suitable sheet metal, for example, and supported in any suitable way well known in the art at the ceiling of the room. The lamp housing 10 has one pair of opposed side walls 12a and 12b and a second pair of opposed side walls, of which only the wall 14 is visible in the drawings. All of these side walls terminate in bottom edges which define an open bottom for the housing 16, and FIG. 1 illustrates the bottom edges 16a and 16b of the walls 12a and 12b, respectively, While FIGS. 2, 5 and 6 show the bottom edge 18 of the wall 14, and of course the other wall 14 which is not visible is identical with that shown in the drawing.

The pair of opposed side walls 12a and 12b of the housing 10 respectively carry at their bottom edges inwardly directed flanges 20a and 20b which extend toward each other, as shown particularly in FIGS. 1 and 4, and these flanges 20a and 20b terminate at their inner edges, which are nearest to each other, in upwardly directed lips 22a and 22b, as indicated in FIGS. 1 and 4.

The lighting fixture includes a diffuser plate 24 which may be transparent or white and translucent and made of a suitable light-weight plastic, well known in the art, and this difiuser plate 24 has an upper surface 26 (FIG. 3) directed upwardly toward the interior of the housing and a lower, downwardly directed surface 28 which may be formed over its entire area with cut-off prisms P to efliciently redirect the light away from glare angles.

The diffuser plate 24 has two pairs of opposed side edges, and one of these pairs of opposed side edges 30a and 30b respectively rests on the flanges a and 20b when the diffuser plate 24 is in its operative position located in and substantially filling the open bottom of the housing 10. As is apparent particularly from FIG. 1, the pair of opposed side edges a and 30b of the plate 24 are respectively formed with shoulders 32a and 32b spaced from the bottom surface 28 by a distance substantially equal to the extent to which the lips 22a and 22b extend upwardly from the flanges 20a and 20b, respectively, so that in this way these shoulders engage the upper edges of the lips of the flanges 20a and 20b to situate the lower surface 28 of the plate 24 in the same plane as the lower surface of the flanges 20a and 20b.

The other pair of opposed side edges of the diffuser plate 2.4 are respectively provided with walls 34a and 34b, shown respectively in FIGS. 1 and 3, so that in this way the upwardly directed flanges, which form the edges 30a and 30b, and the walls 34a and 34b, all of which are integral with the plate 24, give the plate 24 a strength and rigidity which enable it to remain in a flat, non-sagging condition, even though this plate 24 is of a substantial area and made of a light-weight plastic which in simple sheet form is fairly flexible.

The side wall 14 and the side wall parallel to the side wall 14 but not illustrated carry a pair of coaxial pins 36 which extend parallel to and are located adjacent the flange 20a. These pins 36 are situated above the bottom edges of this other pair of opposed side walls, of which only the wall 14 is visible in the drawings, and of course only one of the coaxial pair of pins 36 is shown in the drawings. As may be seen from FIG. 2, the pins 36 are simply riveted directly to the side walls 14 so that they extend perpendicularly therefrom and are rigidly fixed therewith.

The diffuser plate 24 integrally carries at its opposed side edges, which are respectively shown in FIGS. 1 and 3, a pair of hook means a and 401) which respectively receive the pair of coaxial pins 36, and this pair of hook means 40a and 40b cooperates with the pair of coaxial pins 36 to support the diffuser plate 24 in an open position hanging downwardly from the pins, as described in greater detail in connection with FIGS. 4-6 so that in this way free access may be had to the interior of the lamp housing, as is particularly apparent from FIG. 6.

The pair of opposed side walls 14 also carry a second pair of coaxial pins 38, only one of which is visible in FIGS. 1 and 4, and these pins 38 are fixed in the same way as the pins 36 to the pair of opposed side walls 14 of the housing 10. The pair of coaxial pins 38 have with respect to the flange 20b precisely the same relationship that the pair of coaxial pins 36 have with respect to the flange 20a, so that in this way the diffuser plate 24 may be mounted in the lamp housing either in the position shown, where the pair of hook means 40a and 40b cooperate with the pins 36, or in a position displaced by 180 from the position shown in the drawings and where the pair of book means 40a and 40b will cooperate with the pair of pins 38.

It is to be noted in this connection that the pins 36 and 38 are of an exceedingly simple and inexpensive construction, while on the other hand the pair of hook means are of a more complex construction. Wit-h this arrangement of the invention. According to which the pair of hook means are carried by the diffuser plate rather than by the lamp housing, it is possible to provide only one set of hook means so that the more complex structure is not duplicated, and at the same time it is possible to mount the diffuser plate interchangeably with either of its longitudinal side edges engaging either of the flanges 20a or 20b. Of course, what is shown in FIGS. 1 and 3 are the narrow side edges which are respectively located at the ends of the elongated diffuser plate, while the elongated side edges thereof rest on the lips 22a and 2211 as described above. Thus, with this arrangement it is possible to have the plate 24 reversed so that the hooks 40a and 40b cooperate with the pins 38, and the structure will operate in precisely the same way. This is in contrast with a structure where elements similar to the hooks 40a and 40b form part of the housing 10 and elements which correspond to the pins 36 are carried 'by the diffuser plate. With such a construction while the diffuser plate may be somewhat simpler because it is only provided with a pair of pins, nevertheless it is necessary to duplicate what corresponds to the pair of hook means of the invention, so that two pairs of hooks are required to cooperate with the single pair of pins carried by the diffuser plate, and thus a far more expensive construction results.

Of course, one of the reasons why one would normally be reluctant to provide the diffuser plate with structures corresponding to the hook means 40a and 40b is that because of the relatively substantial size of these elements it would be expected that they would provide fairly dark, localized areas on the diffuser plate blocking the light from passing therethrough, and in fact precisely this drawback is present with diffuser plates which carry pivot pins since such diffuser plates must be provided with built up boss portions to properly receive such pins. However, according to a further feature of the invention this drawback is avoided. Thus, it will be seen from FIGS. 1 and 3 that the pair of hook means 40a and 40b are formed by a pair of blocks 42a and 42b which extend inwardly from and are integral with the walls 34a and 34b, respectively and the hook-shaped configuration is given to these blocks not only by the configuration of the outer surface thereof but also by forming in the blocks the notches 44a and 44b which extend inwardly from the outer faces f the block portion 42a and 42b, which are flush with the outer faces of the walls 34:: and 34b, toward, but terminate short, of the inner surfaces of the blocks which are spaced inwardly of the walls 34a and 34b, the inner surface 43 of the block 42a being visible .in FIG. 1. In this way the pair of hook means are exceedingly rugged and rigid because they are formed by solid blocks, so that they can cooperate with the pins to give the desired support for the relatively light diffuser plate 24.

As was mentioned above the blocks of the invention do not provide localized areas which are substantially darker than the rest of the diffuser plate when the light passes through, and this result is brought about first of all by the fact that the blocks are integrally fabricated with the transparent plate and are therefore also transparent. Secondly the blocks 42a and 42b are slightly spaced above the upper surface 26 of the diffuser plate. Thus, as may be seen from FIG. 1 the block 42a has a botom surface 46a, and as may be seen from FIG. 3 the block 42b has a bottom surface 46b, and these bottom surfaces 46a and 46b are spaced above the upper surface 26 of the diffuser plate by a distance suflicient to permit some of the light to pass into the space between the blocks and the diffuser plate surface 26 so that the cut-off prisms P can redistribute the emitting light beneath the blocks in the same manner as throughout the rest of the plate. Thus undesirable irregular light patterns at the areas where the blocks or hook means 40a and 40b are located are minimized with this feature of the invention.

As was pointed out above, the structure of the invention is such that the pair of hook means 40a and 40b can cooperate either with the pair of coaxial pins 36 or with the pair of coaxial pins 38, and according to a further feature of the invention a cam means 48a, 48b is provided to cooperate with that pair of pins which is not received in the pair of hook means so as to contribute to the guiding of the diffuser plate between its open position shown in FIG. 6 and its operative closed position shown in FIG. 1. The pair of cam means 48a, 481; are formed by inclined surface portions of the upper edges of the walls 34a and 3417, these inclined camming portions extending upwardly beyond the elevation of the remainder of the upper edges of the walls 34a and 34b, as is apparent from FIGS. 1 and 3.

Assuming that the diffuser plate 24 is in the position shown in FIG. l resting on the flanges 20a and 20b, and that it is desired to have access to the interior of the housing 10, then the operator will first raise the diffuser plate 24 in the direction of the arrow 50 shown in FIG. 4 and will then shift the diffuser plate horizontally in the direction of the arrow 52 shown in FIG. 4, and it will be noted that the side edges 30a and 30b of the plate are spaced from the walls 12a and 12b by a distance sufficient to afford lateral shifting movement as indicated from a comparison of FIGS. 1 and 4.

As may be seen from FIG. 1, the only possible movement of the diffuser plate 24 from the position in FIG. 1 is in an upward direction, so that even if the operator does not remember how to move the diffuser plate he will necessarily move it upwardly in the direction of the arrow 50 of FIG. 4. Moreover, it will be seen that the configurations of the hook means 40a and 40b are such that if the operator after shifting the diffuser plate upwardly attempts to shift the difluser plate to the right, as viewed in FIGS. 1 and 4, then a solid portion of the blocks 42a and 42b by their engagement with the pins 36 will prevent such movement, so that the operator can only move the plates to the left, in the direction of the arrow 52 of FIG. 4, after first raising the plate, and it will be seen that the configuration of the hook means of the invention leaves the operator only these choices of movement and all other movements are reliably prevented, so that with the construction of the invention all that the operator can do is shift the plate from the position of FIG. 1 first in the direction of the arrow 50 and then in the direction of the arrow 54 into the position of FIG. 4. It will be noted that this movement places the camming means 48a and 48b in engagement with the pair of pins 38, so that as the operator shifts the diffuser plate 24 in the direction of the arrow 52 the camming edges 48a and 48b respectively cooperate with the pins 38 to cam the right edge of the diffuser plate, as viewed in FIG. 4, downwardly, and thus the structure itself forces the diff-user plate to start to turn in a clockwise direction, as shown by the arrow of FIG. 5, around the pair of pins 36, and of course because the plate 24 has been shifted to the position of FIG. 4 it is only the right edge of the plate, as viewed in FIG. 4, that can move downwardly past the flange 2%, so that the operator will simply allow the diffuser plate 24 to swing downwardly, as shown in FIG. 5, with the pins 36 being received in the uppermost portions of the pair of hook means 40a and 40b, and from this point on it is a simple matter for the diffuser plate to swing into the position shown in FIG. 6 where it simply hangs downwardly from the pair of coaxial pins 36, thus giving free access to the interior of the lamp housing. Of course, the plate 24 will be returned to the position of FIG. 1 through the reverse of the above operations, the operator turning the plate 24 upwardly through the position of FIG. back into the position of FIG. 4 and then shifting the plate first in the direction opposite to that indicated by the arrow 52, whereupon the operator can simply allow the diffuser plate to drop down to the position where the shoulders 32a and 32b engage the lips 22a and 22b, respectively.

When the diffuser plate is initially assembled with the lamp housing the pair of hook means 40a and 49b are passed upwardly between the pair of pins 36 and the flange 20a, and then the pair of pins 36 are received in the spaces 54 of the pair of hook means (FIG. 3) and the tips 560 and 56b of the hooks are displaced around the pins so that they will be received in the interior of the pair of hook means. Through this simple operation the diffuser plate 24 is assembled with the housing, and of course should the operator so desire these hook means could instead have been assembled with the pins 38, in which case the camming edges 48a and 48b would cooperate, in precisely the manner described above, with the pins 36.

It will thus be seen that with the structure of the invention there is no possibility of tearing or otherwise damaging the diffuser plate 24, even though the operator may not remember precisely how to displace the diffuser plate from the position of FIG. 1 into the position of FIG. 6, since the structure of the invention necessarily compels the operator to manipulate the diffuser plate in only one way, and furthermore the structure is exceedingly simple since in a preferred form it requires only two sets of pins and one pair of hook means. Even though this pair of hook means is formed integrally with the diffuser plate, nevertheless, because it is spaced from the upper surface 26 thereof and because it is fabricated of the same material as the plate, undesirable light patterns are minimized at the light emitting areas beneath the hook means.

While specific embodiments of the invention have been described, it is apparent other modifications will occur to those skilled in the art, and it is to -be understood that the specific embodiments are not presented by way of limitation but that the present invention comprehends all constructions coming within the scope of the appended claims.

What is claimed is:

1. A lighting fixture comprising a lamp housing having a first pair of opposed walls terminating respectively in a pair of opposed inwardly directed bottom flange portions,

said housing having a second pair of opposed walls terminating respectively in a pair of opposed flangeless bottom edge portions, said pair of bottom flange portions and said pair of bottom edge portions defining a bottom opening in said housing,

a light-transmitting difiuser member located normally in a closed position substantially in said bottom opening in said housing,

said diffuser member having a first pair of opposed bottom edge portions,

said diffuser member having a second pair of opposed bottom edge portions normally resting respectively on said flange portions of said first pair of opposed walls of said housing,

said second pair of opposed walls of said housing respectively carrying a pair of coaxial pivot pin means which extend from said second pair of opposed walls toward each other for pivotally supporting said diffuser member in its open position,

said diffuser member having respectively adjacent its said first pair of opposed bottom edge portions and in the vicinity of one of its pair of second opposed edge portions a pair of light-transmitting hook means which respectively receive said pivot pin means, after said diffuser member has first been raised and moved from said closed position, to support said diffuser member for swinging movement about the common pivot axis of said pin means to its open position hanging from said pin means to give access to the interior of said housing.

2. A lighting fixture comprising a lamp housing having a first pair of opposed walls terminating respectively in a pair of opposed inwardly directed bottom flange portions, said housing having a second pair of opposed walls terminating respectively in a pair of opposed flangeless bottom edge portions, said pair of bottom flange portions and said pair of bottom edge portions defining a bottom opening in said housing, a light-transmitting diffuser member located normally in a closed position substantially in said bottom opening in said housing, said diffuser member having a first pair of opposed bottom edge portions, said diffuser member having a second pair of opposed bottom edge portions normally resting respectively on said flange portions of said first pair of opposed walls of said housing, said second pair of opposed walls of said housing respectively carrying two pairs of coaxial pivot pin means which extend from said second pair of opposed walls toward each other, said diffuser member having respectively adjacent its said first pair of opposed bottom edge portions and in the vicinity of one of its pair of second opposed edge portions a pair of light-transmitting hook means which respectively receive one of said two pairs of said pivot pin means, after said diffuser member has first been raised and moved from said closed position, to support said diffuser member for swinging movement about the common pivot axis of said one pair of pin means to its open position hanging from said one pair of pin means to give access to the interior of said housing, whereby when said diffuser member is assembled with said housing said pair of hook means may interchangeably cooperate with either one of said pairs of coaxial pivot pin means.

3. A lighting fixture comprising a lamp housing having a first pair of opposed walls terminating respectively in a pair of opposed inwardly directed bottom flange portions terminating at their edges which are nearest to each other in a pair of upwardly directed lips respectively, said housing having a second pair of opposed walls terminating respectively in a pair of opposed flangeless bottom edge portions, said pair of bottom flange portions and said pair of bottom edge portions defining a bottom opening in said housing, a light-transmitting diffuser member located normally in a closed position substantially in said bottom opening in said housing, said diffuser member having a first pair of opposed bottom edge portions, said diffuser member having a second pair of opposed bottom edge portions having 'at its lower downwardly directed surfaces a pair of shoulders extending along said first pair of opposed walls and resting on said lips, said shoulders being spaced from the lower surface of said diffuser member by a distance substantially equal to the extent to which said lips extend upwardly from said flange portions so that the lower surface of said diffuser member is substantially flush with the lower surface of said flange portions, said second pair of opposed walls of said housing respectively carrying a pair of coaxial pivot pin means which extend from said second pair of opposed walls toward each other for pivotally supporting said diffuser member in its open position, said diffuser member having respectively adjacent its said first pair of opposed bottom edge portions and in the vicinity of one of its pair of second opposed edge portions a pair of light-transmitting hook means which respectively receive said pivot pin means, after said diffuser member has first been raised and moved from said closed position, to support said diffuser member for swinging movement about the common pivot axis of said pin means to its open position hanging from said pin means to give access to the interior of said housing.

4. A lighting fixture comprising a lamp housing having a first pair of opposed walls terminating respectively in a pair of opposed inwardly directed bottom flange portions, said housing having a second pair of opposed end walls terminating respectively in a pair of opposed flangeless bottom edge portions, said pair of bottom flange portions and said pair of bottom edge portions defining a bottom opening in said housing, a light-transmitting diffuser member located normally in a closed position substantially in said bottom opening in said housing, said diffuser member having a first pair of opposed bottom edge portions, said diffuser member having a second pair of opposed bottom edge portions, normally resting respectively on said flange portions of said first pair of opposed walls of said housing and being spaced from said first pair of opposed walls by a distance slightly less than the width of said bottom flange portions, said second pair of opposed walls of said housing respectively carrying a pair of coaxial pivot pin means which extend from said second pair of opposed walls toward each other for pivotally supporting said diffuser member in its open position, said diffuser member having respectively adjacent its said first pair of opposed bottom edge portions and in the vicinity of one of its pair of second opposed edge portions a pair of light-transmitting hook means which respectively receive said pivot pin means, each of said pair of hook means having its uppermost recessed surface portion extending substantially above the respective one of said pin means when said diffuser member rests on said flange portions and freeing said diffuser member for upward movement from said flange portions and then for horizontal shifting movement over the flange portion remote from said hook means and away from the flange portion adjacent said hook means so that the bottom edge portion of said diffuser member which normally rests on said remote flange portion can swing downwardly past the latter while said uppermost recessed surface portions of said pair of hook means respectively engage said pin means, to support said diffuser member for swinging movement about the common pivot axis of said pin means to its open position hanging from said pin means to give access to the interior of said housing.

5. A substantially rectangular lens for normally substantially horizontal disposition beneath light source means in a fixture having stationary pivot pin elements supported by the housing for pivotally supporting said lens in its open position,

said lens comprising a unitary structure fabricated of light-transmissive material and including a web having a light-incident surface and a light-emergent surface,

and including integrally formed and axially aligned opposed hook means extending substantially perpendicularly to said web for receiving the pivot pin elements of the fixture,

said hook means forming respective notches which extend beneath the upper surfaces thereof and which respectively open upwardly at the free end of said hook means for permitting entry respectively therein of the pivot pin elements of the fixture,

each of said hook means having the uppermost surface portion of its notch shaped to engage the respective stationary pivot pin elements for pivotal support thereat of said hook means and said web after said web has been raised and moved from said normal horizontal position of the lens, lower portions of said hook means forming the lower surfaces of said notches, said lower portions of said hook means having surfaces which are below said lower surfaces of said notches and which are located above the light incident surface of said web to define therewith respective light passages which receive incident light rays directly from the light source means and which permit said incident light rays to pass directly onto said light-incident surface without striking said hook means.

6. A lens according to claim 5 wherein each said light passage is a slot defined by a generally horizontal upper surface formed in the lower portion of the respective hook means and by a pair of generally vertical side surfaces formed in said respective hook means and further defined at its lower surface by the portion of said light-incident surface of said web over which said respective hook means is located.

7. A lighting fixture comprising a housing having two pairs of opposed side walls all terminating in a peripheral bottom portion which defines an open bottom of said housing, one of said pairs of opposed side walls having adjacent the bottom edges thereof a pair of inwardly directed flanges, respectively, which extend toward each other, a diffuser plate located in and substantially filling said open bottom of said housing and having two pairs of opposed side edges, the side edges of one of said pairs of said side edges resting respectively on said flanges, the other of said pairs of opposed side walls of said housing carrying above said bottom edges thereof two pairs of coaxial pins which extend toward each other, one of said pairs of coaxial pins being located adjacent and extending substantially parallel to one of said flanges and the other of said pairs of coaxial pins being located adjacent and extending substantially parallel to the other of said flanges, said diffuser plate carrying at the other of said pairs of opposed side edges thereof a pair of hook means which respectively receive said one pair of coaxial pins and cooperate therewith to support said diffuser plate in a position hanging downwardly from said one pair of coaxial pins to give access to the interior of said housing when said plate is raised slightly from said flanges and swung substantially around the common axis of said one pair of pins, said diffuser plate carrying at said other of said pairs of opposed side edges thereof and adjacent the other of said pairs of coaxial pins a pair of camming means which cooperate with the other of said pairs of said coaxial pins to earn the side edge of said plate which normally rests on the other of said flanges downwardly out of said open bottom of said housing when said plate is raised from said flanges and shifted toward one of said one pair of opposed side walls of said housing preparatory to swinging said plate downwardly to its hanging position.

8. A lighting fixture as recited in claim 7 and wherein said two pairs of coaxial pins respectively have precisely the same relationships with respect to said flanges so that said pair of hook means may cooperate with either one of said pairs of coaxial pins while said pair of camming means will automatically cooperate with the pair of coaxial pins which are not received in said pair of hook means.

9. A lighting fixture comprising a lamp housing having two pairs of opposed side walls all terminating in a. peripheral bottom portion which defines an open bottom of said housing, one of said pairs of opposed side walls having adjacent its bottom edges a pair of inwardly directed flanges which extend toward each other, a diffuser plate located in and substantially filling said open bottom of said housing and having two pairs of opposed side edges, the side edges of one of said pairs of side edges resting respectively on said flanges, the other of said pairs of said side walls of said housing carrying two pairs of coaxial pins located above the bottom edges of said other pair of opposed side walls and extending substantially parallel to and located respectively adjacent said flanges, said diffuser plate having at the other of said opposed edges thereof a pair of walls which extend from an upper surface of said plate, which faces the interior of said housing, upwardly in said housing, said pair of walls of said plate being formed integrally with said diffuser plate and integrally carrying a pair of hook means which respectively receive one of said pairs of coaxial pins to support said diffuser plate for swinging movement from its position in said open bottom of said housing to a position hanging from said one pair of pins to give access to the interior of said housing, said pair of walls of said plate respectively having a pair of upper edge portions which are inclined and cooperate with the other said pair of coaxial pins to cam the one of said one pair of side edges of said diffuser plate which is adjacent said other pair of coaxial pins downwardly out of said open bottom of said housing when said plate is raised from the flanges of said housing and shifted toward one of said one pair of opposed side walls preparatory to being swung about said one pair of pins to its position hanging therefrom.

10. A lighting fixture as recited in claim 9 and Wherein said pair of hook means are integral with said pair of walls, respectively, of said diffuser plate and are of the same material as said difluser plate and are formed re spectively by a pair of block portions which extend from said last-mentioned walls inwardly toward each other and are spaced from said upper surface of said plate sufiiciently so that the light which passes through said plate will be able also to pass through the portion of said plate which is beneath the said pair of hook means, the light emitting surface of said diffuser plate having prism means formed thereon for redirecting the light which passes therethrough.

11. A lighting fixture as recited in claim 10, said block portions which form said pair of hook means having outer face portions substantially flush with outer faces of said last-mentioned walls, which face away from each other, and having inner face portions spaced inwardly from the inner faces of said last-mentioned pair of walls, respectively, and said pair of block portions being formed with notches extending from said outer face portions thereof, inwardly toward but terminating short of, said inner face portions thereof and giving said block portions a hook-shaped configuration.

12. A substantially rectangular lens for substantially horizontal disposition beneath horizontally oriented linear light source means in a fixture having pin elments for hinging said lens, said lens comprising a unitary structure fabricated of light transmissive material and including a web with a light incident and a light emergent surface and walls extending perpendicularly to said web from the edges thereof, a pair of said walls opposing one another and including integrally formed and axially aligned hook elements for receiving the pin elements of the fixture; the outer surfaces of said hook elements being substantially flush with the outer surfaces of their respective walls, the inner surfaces of said hook elements being spaced inwardly from the inner surface of their respective walls, said hook elements forming notches respectively which extend beneath the upper surfaces thereof, said notches respectively opening outwardly of said walls and upwardly at the free end of said hook elements for permitting entry of the pin elements of the fixture, the bottommost portions of said hook elements forming the lowermost surfaces of said notches, said lower surfaces formed by said bottommost portions being spaced above the light incident surface of said web.

References Cited UNITED STATES PATENTS 2,978,575 4/1961 Cohen 2405-1.11 3,192,381 6/1965 Zurawski et al. 240-147 NORTON ANSHER, Primary Examiner.

C. R. RHODE, CHARLES C. LOGAN,

Assistant Examiners. 

1. A LIGHTING FIXTURE COMPRISING A LAMP HOUSING HAVING A FIRST PAIR OF OPPOSED WALLS TERMINATING RESPECTIVELY IN A PAIR OF OPPOSED INWARDLY DIRECTED BOTTOM FLANGE PORTIONS, SAID HOUSING HAVING A SECOND PAIR OF OPPOSED WALLS TERMINATING RESPECTIVELY IN A PAIR OF OPPOSED FLANGELESS BOTTOM EDGE PORTIONS, SAID PAIR OF BOTTOM FLANGE PORTIONS AND SAID PAIR OF BOTTOM EDGE PORTIONS DEFINING A BOTTOM OPENING IN SAID HOUSING, A LIGHT-TRANSMITTING DIFFUSER MEMBER LOCATED NORMALLY IN A CLOSED POSITION SUBSTANTIALLY IN SAID BOTTOM OPENING IN SAID HOUSING, SAID DIFFUSER MEMBER HAVING A FIRST PAIR OF OPPOSED BOTTOM EDGE PORTIONS, SAID DIFFUSER MEMBER HAVING A SECOND PAIR OF OPPOSED BOTTOM EDGE PORTIONS NORMALLY RESTING RESPECTIVELY ON SAID FLANGE PORTIONS OF SAID FIRST PAIR OF OPPOSED WALLS OF SAID HOUSING, SAID SECOND PAIR OF OPPOSED WALLS OF SAID HOUSING RESPECTIVELY CARRYING A PAIR OF COAXIAL PIVOT PIN MEANS WHICH EXTEND FROM SAID SECOND PAIR OF OPPOSED WALLS TOWARD EACH OTHER FOR PIVOTALLY SUPPORTING SAID DIFFUSER MEMBER IN ITS OPEN POSITION, SAID DIFFUSER MEMBER HAVING RESPECTIVELY ADJACENT ITS SAID FIRST PAIR OF OPPOSED BOTTOM EDGE PORTIONS AND IN THE VICINITY OF ONE OF ITS PAIR OF SECOND OPPOSED EDGE PORTIONS A PAIR OF LIGHT-TRANSMITTING HOOK MEANS WHICH RESPECTIVELY RECEIVE SAID PIVOT PIN MEANS, AFTER SAID DIFFUSER MEMBER HAS FIRST BEEN RAISED AND MOVED FROM SAID CLOSED POSITION, TO SUPPORT SAID DIFFUSER MEMBER FOR SWINGING MOVEMENT ABOUT THE COMMON PIVOT AXIS OF SAID PIN MEANS TO ITS OPEN POSITION HANGING FROM SAID PIN MEANS TO GIVE ACCESS TO THE INTERIOR OF SAID HOUSING. 